THE CHALCIDOID GENUS PEEILAMPUS. 49 



LONGEVITY AND OOGENESIS. 



While tlie Perilampus adults as a usual thing are very short- 

 lived in the laboratory, there is no doubt that they live for a con- 

 siderable period when out of doors under natural conditions. This is 

 indicated b}^ the fact that the females, when newly emerged, never 

 contain eggs within the ovarian tubes, as do those insects which 

 oviposit at once upon emerging. 



In one instance a female was kept alive from April 6 to May 12, 

 a period of 36 days, at the end of which time she was apparently 

 ready to oviposit. Upon dissection approximately 250 eggs, nearly 

 all of which seemed to be ready for deposition, were found. It is 

 probable that man}^ more would have developed had the individual 

 remained alive under natural conditions. 



LENGTH OF LIFE CYCLE AND INFLUENCE OF TEMPERATURE. 



The time required for Penlamims to develop from egg to adult is 

 dependent upon several factors, one of the most important of which 

 is the host. When parasitic upon Varichseta, the planidium beghis to 

 feed early in the spring. On Limnerium validum,, however, the planid- 

 ium must wait until its host begins pupation before it can become 

 external, thus throwing it several days or even weeks behind the 

 individuals infesting Varichxta. 



There are no complete data at hand concerning the development 

 upon Limnerium, owing to the failure of any individual to complete 

 its transformations upon tliis host after removal from the cocoon. 

 Its progress has been followed beyond the first ecdysis several times 

 in the laboratory. In an apparently typical instance a larva of 

 Limnerium containing two planidia was brought into the laboratory 

 from out of doors on Januaiy 28 and placed in an incubator kept at 

 a temperature of 78° F. On the morning of February 4 histolysis 

 had begun, and during the evening of February 5 both planidia had 

 made their exit. Two days later the host larva was apparently dead 

 and the planidia were feeding. February 11 one had molted its 

 first-stage skin, but died a short time later. 



With Varichxta as a host it is a much simpler matter to carry 

 the Perilampus through to maturity. When a single individual is 

 watched through its development more time is required than in 

 undisturbed puparia, owing to the fact that it is impossible to keep 

 the host pupa from deteriorating somewhat. A typical instance of 

 the development upon Varichxta under laboratory conditions follows: 

 On January 28 a pupa of Varichxta with a single planidium was 

 brought in from out of doors and placed in the mcubator. On the 

 next day the ]ilanidium had started to feed and filled up rapicUy. 

 February 1 the distance between the dorsal plates of the planidium 



